On Mon, 1 Feb 2016 13:08:04 -0800 (PST)
Stephen Davenport wrote:

On Monday, February 1, 2016 at 1:11:06 PM UTC-5, Trevor Harley wrote:
Behind the view of flying trees and roofs there was quite a good
display of iridescent (I think they are) clouds this evening.

http://trevorharley.com/trevorharley/Weather.html

Trevor
The Sidlaws, NW of Dundee

========

These are polar stratospheric clouds (PSCs), a.k.a. nacreous clouds.
My news and social feeds are full of pictures of them remarkably far
south (Buckinghamshire, for example). Or perhaps not so remarkably
when you look at how very cold (and moist) the stratosphere is over
the UK due to circumpolar vortex displacement (in turn due to ongoing
stratospheric warming Pacific-side). Temperatures are between -80 and
-85C at 50hPa, for example, and below -85C at 30hPa (and PSCs form
below -78C):

http://users.met.fu-berlin.de/~Aktue...ecmwf50a12.gif

http://users.met.fu-berlin.de/~Aktue...ecmwf30a12.gif



Although one name for these is Polar Stratospheric Clouds it may be
time to drop that. One of the predicted effects of global warming that
was made at least forty years ago was that the stratosphere would cool
most rapidly in the Tropics. A report I saw a couple of years or so
ago said that cooling of 8C had been recorded.

A while ago, I came across a report of iridescent clouds in Central or
tropical South America that someone thought might be nacreous clouds. I
checked the local ascents and found the temperatures were just about
low enough in the stratosphere for that to be possible. I don't think
they were nacreous clouds but I think it's just possible that they may
be seen anywhere.


--
Graham P Davis, Bracknell, Berks. [Retd meteorologist/programmer]
http://www.scarlet-jade.com/
I wear the cheese. It does not wear me.
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